Ceramic glazing composition



106. COMP OSITIONS, Y

comma R PLASUC Patented Feb. 1, 1938 :31, pairs: 1

UNITED STATES PATENT OFFICE 7 i CERAMIC GLAZING COMPOSITION I Edward R. Stowell, Fort Wayne, Ind., assignor of one-half to Worthington Hoyt, Cleveland,

Heights, Ohio No Drawing. Application June 19, 1936, Serial No. 86,084

5 Claims. (01. 106-}6 This invention relates to a glaze or enamel for ceramic products, such as fire bricks and the like to be used for refractory and acid resisting purposes, The principal object is to produce a glaze or enamel on the surface 01' such ceramic. product which Weated will become as hard as the surface to which it 15pm, igg which will not chip mechanical injury to a great extent and will not mural .cfiniers 93311 peratrrres m exces gi ligggjjl, whichwilrresist sfid'd'fiflidVide changes 'ih""Fmperature without cracking or chipping and which will be immune to the action of acids, sulphides, ammonia, chlorine, etc.

It is a further object to produce a slip which can be applied by troweling, brushing, spraying or dipping, which wil uickly without crack ing or peeling, whic cons s 0y 0 non-fiuxing character and a vehicle containing a fluxing agent and an agent capable of giving "green strength and adhesive value to the undried glaze, and which upon drying will not crack and will melt only at temperatures in excess of 3000 F.

The foregoing objects can be realized by bringing together the body consisting of silicon arfines (50 mesh or finer) and containing a suitable quantity of free silica with a suitable quantity of a sodium silicm high soda content (believed to be N'aaSiOaBHzO) with sufiicient to form a stifi dough, allowing a reaction wate to proceed whereby the free silica combines with the soda or the high soda silicate to form a substance having the desired characteristics. For the purpose of facilitating application to the surface to be coated and imparting green strength and adhesiveness to the slip, a suitable quantity of a sodium silicate having a high silica content is added together with a quantity of water to impart proper consistency to the mix.

While it is possible to mix the finely divided silicon carbide and fine y divided silica, I P fer to use a commercial product which is available consisting principally of silicon carbide fines, but containing silica as an impurity to the extent of about 9%. The sodium silicate pentahydrate' is readily soluble in cold water (or hot water) while being relatively nonviscous as compared with ordinary sodium silicate and I prefer to prepare a mixture of the body portion with this compound and water and allow the reaction to become completed before adding the ordinary sodium silicate solution and the final amount of Silicon carbide water, the ordinary silicate being viscous and added for the purpose of giving green strength to the composition and for imparting rapid drying qualities thereto. This latter silicate is added in dry form.

One example of the composition is given as follows:

to 88% Silica (preferably contained in }98% to 97% the Silicon carbide) to Sodium silicate (N810, SiOg ratio 1:1) Water sufficient to produce a dough Sodium silicate (N310, SiOa ratio 1:2) (powder) 2% to 10% Water suilicient to give desired consistency In the above example, the ingredients with the exception of the last two are brought together and allowed to react, after which the ordinary silicate is added in the dry form and the resulting slip reduced to the desired consistency with such quantity of additional water as is required. The reaction takes place suitably in the cold, that is, from 50 F. to about F., and is complete in approximately 3 to 4 hours. Where thicker films are to be applied more of the ordinary viscous silicate is employed; for thin films less, as indicated.

Having thus described my invention, what I claim is:

1. A process of making a slip" for glazing ceramics, comprising bringing together a major portion of finely divided silicon carbide with a small proportion of finely divided silica and a small proporton of a sodium silicate compound of relatively low viscosity and water, allowing the silica to react with the silicate and finally adding a sodium silicate compound of relatively high viscosity and water sumcient to reduce the mass to a suitable consistency for brushing, spraying or dipping.

2. A process of making a slip for glazing ceramics, comprising bringing together a quantity of silicon carbide containing about 5% to 12% of free silica with about two to three percent of its weight of sodium silicate of Nero, SlOz, ratio approximately 1: 1, and water sufficient to form a doughy mass, allowing the reaction between such silicate and free silica to become complete, adding about two to ten percent of sodium silicate of NazO, SlOz ratio approximately 1:2, in dry form. and water suflicient to reduce the mass to a suitable consistency for brushing, spraying or dipping, but not exceeding one third of the total weight of the mixture.

3. A process of making a slip for glazing ceramics, comprising bringing together a quantity of silicon carbide containing about 5% to 12% of free silica with about two to three per- Examiner cent of its weight of sodium silicate of relatively high soda content and water suflicient to form a doughy mass, allowing the reaction between such silicate and free silica to become complete, adding in dry form about two to ten percent of sodium silicate of relatively low soda content and water suflicient to reduce the mass to a suitable consistency for brushing, spraying or dipping.

4. A slip for glazing ceramics comprising the reaction product of silicon carbide and free silica, finely divided and thoroughly admixed with sodium silicate of relatively high soda content, together with dry sodium silicate of relatively low soda content and water suflicient to produce 9,

suitable consistency for brushing, spraying or pp ng.

5. A slip for glazing ceramics comprising the reaction product of silicon carbide containing 5% to 12% free silica with 2% to 3% of sodium silicate of NazO, SiOz ratio approximately 1:1, and water suflicient to produce a stiff dough, with 2% to 10% of sodium silicate of NazOSiOz ratio approximately 1:2 and water suflicient to produce a consistency suitable for application by brushing, spraying or dipping.

EDWARD R. STOWELL. 

